70 TRANS. OF THE ACAD. OF SCIENCE. 



Difference of Temperature and of Relative Humidity in 

 City and Country. By George Engelhann, M.D. 



At a former occasion (Jan. 10, 1860, Trans. Vol. I., p. 693) 

 I communicated to the Academy a Paper on the Difference 

 of Temperature of the City and the Country near St. Louis ; 

 and proved by a table of comparative observations, made 

 in the year 1859 by Mr. A. Fendler, in the valley of Rock 

 Spring creek, near the Pacific Railroad machine shop, and by 

 myself at the corner of Elm and Fifth streets, that the tem- 

 perature outside the city is lower than in the heart (the 

 closely built up part) of the city. Mr. Fendler elaborated 

 the same theme more fully in an interesting article published 

 in the Smithsonian Report for 1860, p. 403. 



Mr. Fendler's observations for 1860 were fragmentary, 

 but, as far as they went and could be compared, they indica- 

 ted the same facts. Towards the end of that year he trans- 

 ferred the field of his labors to Tower Grove, Mr. H. Shaw's 

 Missouri Botanic Garden, and there he has most assiduous- 

 ly continued his meteorological observations. From his jour- 

 nals, kindly communicated to me, and my own, I have com- 

 piled the following tables. 



The Missouri Botanic Garden is situated on a moderate 

 rise in the centre of a wide prairie, now entirely under culti- 

 vation, surrounded at the distance of one mile or more by 

 ranges of gently sloping hills or ridges; it lies to the^ south- 

 west from the city proper, about three miles distant ; its ele- 

 vation is a little higher than that of my station. 



The table on the next page explains itself; it gives the 

 mean of the monthly observations made at both points of ob- 

 servation at the hours of 7 A. M., 2 P. M., and 9 P. M., and 

 their differences ; also the monthly means and extremes, and 

 their differences. The extremes, it is necessary to observe, 

 are not absolute, Mr. Fendler having failed _ to observe the 

 temperature at sunrise, when, generally, it is lowest ; they 

 are only the extremes at the hours of observation. 



The table proves again that the mean temperature is 

 higher in the city than in the country ; and further, when 

 compared with former observations, that the difference of 

 temperature between my location and the Missouri Botanic 

 Garden is greater than between the same place and Mr. 

 Fendler's former place of observation, no doubt, because far- 

 ther removed from the influences of the city. 

 The differences were found to be : 



1859, at 7 A. M., 1.8 ; at 2 P. M., 0.3 ; at 9 P. M., 2.1 : mean, 1.4. 

 1861 ; « 2.1; " 1-5; " 2.8: " 2.1. 



